Jingle Bells" using BT66T / UM66, Circuit made on a Breadboard - YouTube
microcontroller - Why does the voltage drop when I connect an 8 ohms 1 watt speaker, specifically the source to the circuit is GPIO pin output voltage? - Electrical Engineering Stack Exchange
UM66 melody circuits & 4 melody ICs | How to make the UM66T melody circuit - YouTube
Build Touch Door Bell Alarm Circuit using TTP226 Touch Sensor Module a – QuartzComponents
UM66 IC and UM3561 IC for Melody and Sirens generation
Melody Generator Circuit Diagram
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TA66T19L BT66T-19L UM66T19L Sound Melodie IC / GENERATOR | eBay
BT66T/UM66 Melody Generator IC #BT66 #UM66 #melody - YouTube
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